960sqft plus an extra deep 1 car garage for two adults, a large dog, and two cats. We basically don't use one of the bedrooms so we could probably go down to 7-800. My main concern of we were to have a kid would be wanting another bathroom once it started potty training
Updating to add details:
TLDR version: we're pretty minimalist, but have room for bikes, a VR system, game nights with friends (including tons of board games), and tools for remodeling work. We rarely have overnight guests but can house 1 or 2 at a time.
2 Bed, 1 Bath townhome with an extra deep 1 car garage, a driveway big enough for 1 car, the possibility of a free spot in the HOA guest parking, or plenty of street parking just outside of the HOA (we're right on the edge so actually more convenient than the guest spots).
We both drive so whoever gets home first gets the garage spot, and the other person gets the driveway. Occasionally, if timing doesn't work out, we'll drive the other person's car and it's no big deal. We each have a bike which fit fine in the garage with the car. We have shelving in there to hold tools (including a folding table saw, a chop saw, and everything else we used to remodel the house), camping gear, and any miscellaneous stuff we don't want in the house. I have a pile of things to be donated out there too and once they're gone it will be downright spacious.
Inside there's a galley kitchen which is wider than you typically see and well setup with counters on each side of the stove and next to the fridge. I don't use a lot of single purpose kitchen stuff (though you can pry my rice cooker out of my cold dead hands) so everything fits pretty well even though it's fairly small. When we remodeled I insisted on an over-the-range microwave to open up counter space.
The living room is large enough to play VR in, and we opted to use folding tv trays instead of a coffee table to make this easier (and get rid of flat surfaces to accumulate crap).
There's a semi-formal dining room. We bought a table with self-storing leaves so when it's just the two of us there's plenty of room to get around it, but will extend to easily seat 6, and cozily seat 8. The table has 4 chairs and we have two camp chairs and a computer chair as spares when needed. There's also two bookshelves with 18" deep cabinets on the bottom half that store our books and board games (plus another bottom cabinet part in the living room for more games). We host D&D sessions often and board game nights once a month. We have had friends bring extra chairs and folding tables to set up in the living room and office when we've hosted larger-than-normal game nights with multiple games going
The bathroom is very standard-bathroom-esque but has a closet with the washer and dryer in it. I opted for a stacked set so we could have a custom cabinet built in there and add quite a bit of storage for linens, cleaning supplies, etc.
One bedroom is a bedroom and only has bedroom things (bed, dressers, night stands, clothes, dog bed).
The other bedroom is in progress (and the one I said we rarely use and could do without) but will become my office/exercise room with computer desk, a loveseat sized sofa bed (don't own yet, but it's on the list to buy, for now we use an air mattress) for the occasional guests, and small exercise stuff like a few sets of dumbbells and a foam roller. We can accommodate 1-2 overnight guests, but when my in-laws visit with my two pre-k nieces they get a hotel room. The closet in there is our catch-all closet for things that don't belong anywhere else plus DH's Warhammer stuff and some miscellaneous D&D stuff we don't use regularly.
We have a fenced in yard, but it's shared with our adjoining 4 neighbors (5 unit townhome). We have an end unit so we get the side and directly behind us so it's quite a bit of space. We got a 30' run line for the dog so we can tie him out to do his business, but he's very lazy and spends most of his time inside. It would be harder to have the shared back yard with a high energy dog.